Down draft-furnace



(No Model.) 2Sheets-SheetL ORLAND D. ORVIS & ORBL D. ORVIS.

. DOWNDRAFT FURNACE.

No. 486,122. Patented NOV. 15,1892.

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(Nb Model.)

DOWNDRAFT FURNACE.

No. 486,122. Patented Nov; 15, 1892.

m 'yrci xmmwxvum UNITED STATES PATENT OFFICE.

ORLAN D D. ORVIS AND OREL D. ORVIS, OF CHICAGO, ILLINOIS.

DOWN DRAFT-FU RNAC E.

SPECIFICATION forming part of Letters Patent No. 486,122, datedNovember15, 1892.

Application filed April 19,1892. Serial Not 429,735. (No model.) I

To all whom it may concern/.-

Be it known that we, ORLAND D. )RVIS and OREL D. ORVIS, citizens of theUnited States, residing at Chicago, in the county of Cook and State ofIllinois, have invented certain new and useful Improvements inDowndraft- Furnaces, of which the following is a full, clear, and exactspecification.

This invention relates to improvements in downdraft-furnaces in which asteam-boiler, as illustrated, extends directly over the firechambermorespecifically stated, to that class of downdraft steam-boiler furnaces inwhich said boiler, by an arch or diaphragm, is isolated from the directexposure to the burning fuel on the grate-bars, and the cold airnecessarily admitted through the f urnacedoors or other opening in thefire-chamber above the burning fuel to produce a downward draft of theproducts of combustion through grate-bars. In these arch and diaphragmstructures as heretofore arranged there is formed between the arch andthe boiler an air-chamber, the only opening to which, like the entirechamber, is rearward of the line of draft of the furnacethat is to say,rearward of the line of draft of the products of combustion as theyascend from the grate-bars and move onward to the rear of the furnaceand the result is that said chamber is practically a dead-airchamber. In other words, such a chamber isolates all that portion of theboiler-surface immediately over the fire-chamber from the draft heat tosuch a degree that such surface is quite cool as compared with all otherportions beyond the chamber, and certainly the steam-boiler is notheated throughout with that uniformity necessary for the best results,nor are the products of combustion utilized to anything like the extentthey may be capable of in raising the temperature of the contents of theboiler. The seriousness of the objection to this isolation of heat isall the more obvious when it is borne in mind that as usually andordinarily constructed the boiler-surface of a flueless boiler directlyover the fire-chamber and then isolated from the draft heat thereofrepresents about one-fourth of its entire directlyheatable surface, andthat although in flue boilers such as is shown the proportions ofsurface is somewhat lessened it st1ll remains -everportion may bedirectly over the fire chamber, .from all cold air admitted andadmittable to the furnace, both from above the grate-bars to produce adowndraft or from below the grate-bars to supply oxygen to promotecombustion or air for reducing the furnace heat during combustion, andat the same time subject that entire boiler-surface to all of the draftheatin other words, to subject all that portion of a steam-boilersurface ordinarily over the fire-chamber of a downdraftfurnace to all ofthe heat escaping from the grate-bars to the combustion-chamber and todo this without subjecting any portion of said boiler-surface to anycold air admitted to the furnace during its operation.

A further object, in addition to soon ing these desirable results, is toat the same time prevent the formation of smoke during the operation offiring or raking down the furnace.

Another object is to insure as nearly as may be a uniform distributionof the heat to the boiler to be heated as it escapes from the grate-barsthereto.

A still further object is in the utilization of hollow grate-bars forheating boiler-water and to prevent the accumulation of mud and thesediment therein, and at the same time likewise free the boiler fromsimilar accumulation and increase the heating-surface for the water, andfinally to secure other and minor objects by devices and combinations ofdevices hereinafter described, claimed, and shown in the accompanyingdrawings, forming apart hereof, and in which- Figure 1 represents avertical transverse section of a double fire-chamber furnace embodyingour invention in connection with a boiler shown in end elevation; Fig.2, a central longitudinal section of said furnace on the line 2 2 ofFig. 1; Fig. 3,adetail plan view of the grate-bar construction and ofthe muddrum of the same; Fig. 4, a verticaltransverse section of asingle fire-chamber furnace embodying our invention with a steam-boilerin end elevation, and Fig. 5 a detail longitudinal section of the samewith said boiler shown in side elevation.

Similar letters of reference indicate the same parts in the severalfigures of the drawlugs.

A and A indicate the side walls, and B the front end wall; 0 and C, thefire-chamber, and D D ash-pit doorways, the positions of which areindicated by dotted lines in Figs. 1 and 4, and E a steam-boiler, all ofwhich are of the usual construction and arrangement. At the rear end andrising to the top of the ash-pit is a solid wall F, extending from sidewall to side wall of the furnace, upon which is supported a mud-drum G,in turn supporting and in open communication with hollow grate-bars II,which may be pipes in open communication at their forward ends with andattached to a transverse header I, forming a water-chamber common to allof said gratebars, and in turn supported by the walls of the furnace, asindicated in Fig. 3, or in any other suitable manner adapted for itssupport of the grate-bars. The grate-bar structure may be inclined, andinstead of having all of the bars in the same plane, as shown, adjacentbars may be in differing planes and the alternate bars in the sameplane. At that point where there is the greatest; concentration of heatupon the grate-bars in the passage of the products of combustion fromthe grate-bar surface tothe combustion-chamberthat is to say, over whichall the furnace heat must pass in escaping to the combustion chambersaidbars are preferably of larger size and greater internal water capacity,as shown at 11, to increase the heating-surface for the boiler-water.The suppl y-water to the grate-bars is preferably taken from below thewater-line in the boiler, as indicated, by the water-supply pipe orpipes J, which open into the header I, as indicated at J (shown in Fig.3,) and indicated by dotted lines in Fig. 2. In its passage through thegrate-bars back to the boiler, in the direction indicated by the arrowsin Fig. 3, the water enters the mud-drum G, and, depositing the mud andother sediment therein, ascends through the pipe J directly from themuddrum to the boiler at a point preferably above the water-line andcertainly above the plane of the grate-bar supply-pipes, in order toinduce the necessary circulation, it having been found in practice thatthe water heated by the grate-bars is of a very much higher temperaturewhen entering the boiler from the muddrum than when itenters thegrate-bars from the boiler.

The mud-drum G, as shown in Figs. 1 to t, inclusive, serves as a supportfor one side or end of an arch or arches K, which arch or arches, as thecase may be, in connection with the mud-drum, inclose the fire chamberor chambers, so as to prevent the escape of any of the products ofcombustion therein except downwardly through the grate-bars. The arch orarches K may be of fire-brick or other material commonly used for suchpurposes and are so arranged with reference to the boiler immediatelyover the fire-chamber as to provide a combustion-chamber L between saidarch or arches and the boiler, to which chamber the downdraft productsof combustion are conducted, as herein described.

In Fig. 1 our invention is illustrated in connection with a doublefire-chamber furnace in which there is an open space between the gratebars centrally the length of the furnace, and the arches K, supportedupon the grate-bars H at their lower edges and joining the side Walls ofthe furnace at their upper edges, by which arrangement is provided at apoint mid way between the gratebars a passage M, of the same length asthe fire-chambers upwardly, through which the downdraft products ofcombustion from the grate-bars ascend into the combustionchamber overthe fire chambers and have a downdraft therethrough in contact with theboiler as they move onwardly toward the rear of the furnace. By thisconstruction and arrangement of the grate-bars and the arches we havenot only the advantage of subjecting the entire length of thecombustion-chamber immediately over the fire-chamber to the circulationof the products of combustion by a downdraft thereof, and at the sametime the isolation of the boiler from cold air admitted to thefire-chambers, but the advantages due to the use of separatedfire-chambers within the same general furnace structure. Theseadvantages will be understood when it is borne in mind that during thefiring of one chamber the hot products of combustion, passing from theother fire-chamber to the passage M, not only serve to maintain auniformity of heat throughout the combustion -chamber and exclude coldair therefrom, but will ignite in the passage M any waste products dueto the use of fresh fuel and escaping therefrom into the passage M, andhence before they can possibly escape into the combustion-chamber. Inthe use of such double fire-chambers it may also be added that separatedfire-chambers may be more thoroughly raked down and uniformly tired thancould be a single fire-chamber embracing the area of both, and thisbecause there is less fuel to handle at a time and more time to do theraking and firing without reducing the temperature in thecombustionchamber than is possible by the use of a single fire-chamber.Single fire-chambers, however, being frequently desirable, are providedfor by our invention, as shown in Figs. 4 and 5, in Fig. 4 of which isshown a single firechamber, access to which is provided for throughfurnace and ash-pit doors at the front end of the furnace, as indicatedby the dotted lines therein. In this construction there is a spacebetween the side grate-bars H and the walls of the furnace, which barssupport the arch K, inclosing the fire-chamber, the products ofcombustion from which firechamber, after passing downwardly through thegrate-bars, ascend to the combustionchamber L through the passages M ateach side thereof and for the entire length of the fire-chamber.

In order to promote a uniform distribution of the productions to thecombustion-chamber L when such distribution is found necessary, theremay be provided below the gratebars, longitudinally thereof andtransversely of their center, a deflector N, converging at its upper endto an edge and consisting of brick or other suitable material, whichdeflector may also be utilized as a supply to the products of combustionof heated air by means of one or more chambers P, formed therein,communicating with the outside air and provided with openings P in theash-pit for discharging its contents,the heat in the ash-pit serving toheat said deflector, and therefore its contents. In this connection itis proper to observe that instead of utilizing said de-,

flector for supplying heated outside air it may be connected with therear of the furnace to draw off and return to the ash-pit any unconsumedproducts of combustion.

In Fig. 5 we have provided means for drawing all the products ofcombustion from the grate-bars to the forward end of thecombustion-chamber immediately over it, whereby all products ofcombustion are required to traverse the full length of saidcombustionchamber, and to this end the grate-bars extend transversely ofthe furnace, which latter is provided with side doors for firing and forthe ash-pit, as indicated by dotted lines, and terminating the grate-barsurface at a point forward of the front end or wall of the furnacestructure, the arch in this construction extending from side wall toside wall of the furnace and downwardly to and supporting it from thegrate-bar H, the rear end of the arch being supported by the wall F,which, instead of including the mud-drum, is above the grate-bar surfaceto afford such a support.

As in the construction shown in Fig. 5, it may be observed that themud-drum may be omitted in the several other constructions shown in thedrawings; or, on the other hand, the mud-drum may be used in theconstruction shown in Fig. 5, as shown in said other figures.

In conclusion it may be stated that our invention is not limited to thedetails shown, although they illustrate what we believe to be the bestconstruction embodying our invention, for obviously it would be nodeparture therefrom to vary these details and arrangement so long as ina downdraft-furnace cold air admitted to the fire-chamberis isolatedfrom the combustion-chamber and there is immediately over thefire-chamber a portion of that combustion-chamber through which there isa direct draft of the products of combustion from the grate-bar surfaceof such furnace. Neither is our invention limited to its use inconnection with a steamboiler such as is shown, for obviously it isadapted for and can be applied without invention to the fire-chamber ofastationary or locomotive engine or any engine wherein there is over thefire-chamber or at the sides thereof a water-chamber in directcommunication with the contents of that boiler, or to any furnace overthe fire-chamber and which has a heating-oven of any character or aportion of such a heating-oven or hot air chamber.

Having thus described our invention, what we claim as new therein, anddesire to secure by Letters Patent, is-

1. In a downdraft-furnace, the combina tion of the fire-chamber andcombustion-chamber separated from but directly over the firechamber anda draft-passage through which the downdraft products of combustion areconducted into said combustion-chamber at a point forward of its rearend during their on- Ward passage toward the rear end of the furnace,substantially as described.

2. In a downdraft-furnace, thecombination of a combustion chamber orchambers separated from but directly over the firechamber and adirect-draft passage at the side or sides of said fire-chamber, throughwhich the downdraft products of combustion are conducted into saidcombustion-chamber in their onward passage toward the rear end of thefurnace, substantially as described.

3. In a downdraft-furnace, the combination of two or more fire-chambers,a combustionchamber separated from but directly over said fire-chambers,and a draft-passage between said fire-chambers, conducting the downdraftproducts of combustion from the said fire-chambers directly to theoverhead combustion chamber, substantially as described.

4. In a downdraft-furnace, the combination, with the firechamber, of acombustionchamber directly over said fire-chamber, an arch or diaphragmseparating said chambers, and a direct-draft passage or passages betweensaid arch and the wall or walls of the furnace, through which thedowndraft products of combustion from the grate-bars are conducteddirectly to said combustion-chamber, whereby said combustion chamberthroughout its length is subjected to direct draft heat in the passageof the products of combustion from the fire-chambers to the rearport-ion of the furnace, substantially as de scribed.

5. In a downdraftfurnace, the combinachamber immediately over thefire-chamber, tion of the fire-chamber, an arch-like structsubstantiallyas described.

are inclosing the same, a combustion-cham- ORLAND D. ORVIS. her directlyover said grate-bars, and an up- OREL D. ORVIS.

5 draft-passage directly conducting the dowu- Witnesses:

draft products of combustion from the grate- R. C. ()MOHUNDRO,

bars to the forward end of the combustion- F. A. HOPKINS.

